In situ copolymerization of butylene succinate with twice functionalized organoclay: Thermal stability

Biodegradable composites consisting of poly(butylene succinate) (PBS) and layered silicate were prepared by in situ condensation polymerization of 1,4-butane diol and succinic acid in the presence of organoclay containing epoxy groups (TFC) and titanium(IV) butoxide as a catalyst. The intercalation and exfoliation of the clay layers in the biodegradable polyester was examined by X-ray diffraction and transmission electron microscopy. The role of the epoxy groups of TFC was investigated for the improvement of the interfacial interaction between clay and polymer matrix. The PBS/TFC composite has higher degree of exfoliation of the silicate layers than in PBS/Cloisite25A (C25A) one. In this study, the improved thermal stability was attributed to the enhanced interfacial interaction between PBS and TFC through a chemical reaction of the epoxy groups with the end groups of the PBS. Thermal stability of the nanocomposites was studied by thermogravimetric analysis, from which activation energy of thermal degradation was determined by the Kissingerʹs method and the Flynn–Wall–Ozawa one. The activation energy increased in the order of PBS/C25A < PBS < PBS/TFC indicating that the nanocomposite with exfoliated clay platelets was more thermally stable than that with intercalated clay platelets.